23- Lagarteja, Maria Christina2DPh

Kinds of Microscopes1. Simple microscopes- is a microscope containing only one magnifying lens.2. Compound microscopes is a microscope that contains more than one magnifying lens. a. Compound Light Microscope- a compound microscope with built-in light bulb, which is used as the source of illumination.3. Bright-Field Microscope- commonly used in microbiology. Consists of two lenses (objective and ocular lens), which function together to resolve the image.4. Phase Contrast Microscope- can be used to observe unstained living microorganisms.5. Dark-Field Microscope- a light microscope in which the lighting system has been modified to reach the specimen from the sides only through a special condenser. 6. Fluorescence Microscope- used to visualize specimens that fluoresce, which is the ability to absorb short wavelengths of light (UV) and give off light at a longer wavelength (visible light)7. Differential Interference Contrast (DIC) Microscope- employs a polarizer to produce polarized light. It is used in observing unstained cells because of its ability to generate images that reveal internal cell structures that are less apparent by bright-field techniques.8. Electron microscope- uses an electron beam as a source of illumination and magnets to focus the beam.a. Transmission Electron Microscope (TEM)- employs a beam of electros projected from an electron gun and directed or focused by an electromagnetic condenser lens onto a thin specimen.b. Scanning Electron Microscope (SEM)- has a lower resolving power than TEM; however, it is particularly useful for providing three-dimensional images of the surface of microscopic objects.9. Confocal Scanning Laser Microscope (CSLM)- Couples as laser light source to a light microscope.10. Scanning Probe Microscopes- measure surface features by moving a sharp probe over the objects surface.Parts and Uses of MicroscopePartsUses

MAGNIFYING PARTS

1. Eyepiece or ocularEquipped with one set of lenses that magnifies the object several times

2. Objectives:

a) ScannerHas the lowest magnification. It is used to observe wider field of object

b) Low power objective (LPO)Has magnification of 10X, and it is used to observe general outline of the object.

c) High power objective (HPO)Has magnification of 45X. Used in observing the details of the specimen

d) Oil immersion objective (OIO)Has 90-100X magnifications. Uses cedar wood oil, which prevents the refraction or dispersing of light.

ILLUMINATING PARTS:

1. MirrorUsed to reflect light through objective lenses and into the eyes.

2. Abbe condenserUsed to illuminate, condense or concentrate the reflected light from the mirror to the object being examined.

3. Iris diaphragm Used to regulate the amount of light that enters the condenser.

MECHANICAL PARTS

1. Base Supports the whole instrument.

2. PillarVertical extension of the base to which the arm is attached.

3. ArmServes as the handle of the microscope and provides support for the optical parts.

4. Inclination jointsFacilitates tilting of the microscope.

5. StagePlatform where the slide containing the specimen is placed.

6. Stage clipsHolds the slide in place

7. Body tube Serves as a passageway of light from the objective to the eyepiece.

8. Draw tubeHolds the ocular or eyepiece

9. Dust shieldProtects the objective from dust and dirt.

10. Revolving nosepieceFacilitates the shifting of objectives

11. Adjustment knobsUsed to adjust the objectives when focusing which when turned clockwise or counterclockwise, lowers or raises the body tube.

2 types of Adjustment knobs

a) Coarse adjustment knobs or screwsThe larger knobs used for faster movement of the body tube when focusing the LPO.

b) Fine adjustment knobSmaller knobs used for final focusing under HPO and in viewing at different levels.

TERMS:1. Refractive index- measure of the bending of a ray of light when passing from one medium into another.2. Parfocal- refers to the objectives and eyepiece where practically no change in focus has to be made when one objective is substituted for another.3. Working distance- is the distance between the front lens of the objective lens and the top of the cover glass when the specimen is in focus. The higher the magnification, the shorter is the working distance.4. Magnification- is the process of enlarging something only in appearance, not in physical size.5. Total magnification- is determined by multiplying the eyepiece power (usually 10x) by the objective lens in place.6. Focal length- The distance from the center of the lens to this focal point

Uses of microscopes:Microscope plays an important role especially in the field of Microbiology. Some of its uses are: With the help of Microscope, objects that cannot be seen clearly with the naked eye like microorganisms can be seen in microscope. It is used in tissue analysis especially in the diagnosis of diseases. It is used in examining structures of microorganisms. It is used in the identification of things that cannot be seen by the naked eye.Microscopes are used to look at the specimens in better detail.

Sources:1. Engelkirk, P., (2007). Burtons Microbiology for the Health Sciences. Lippincott Williams & Wilkins: Philadelphia, USA.2. Brooks, G., et. al., (2010) Medical Microbiology 25th ed. McGraw-Hill Inc: USA.3. Manual in General Botany with TaxonomyAuthors: Maria Asuncion Crispina S. Cobar, MS Phar. Ophelia S. Laurente, MS. Biological Sciences Ross D. Vasquez, MS Biological Sciences